--- leptonica-1.68.org/src/pngio.c	2012-07-04 21:53:29.380000004 +0000
+++ leptonica-1.68/src/pngio.c	2012-07-04 21:54:09.239000004 +0000
@@ -1,3 +1,4 @@
+#include <zlib.h>
 /*====================================================================*
  -  Copyright (C) 2001 Leptonica.  All rights reserved.
  -  This software is distributed in the hope that it will be
